Defictionalization: Several of the candies displayed in the queue of the Disneyland version were offered for sale once the rest of Toontown reopened, including the Powerlimes sour candy, Scrooge McDuck's Chocolate Coins, and the catchphrase shaped Gollypops.
Died During Production: This is Russi Taylor's final performance as Minnie Mouse since she was able to record all of her dialogue before her passing on July 26, 2019. The ride itself wouldn't open until March 2020.
In Memoriam: The song "Nothing Can Stop Us Now" was dedicated to Russi Taylor after the ride's opening.
Kids' Meal Toy: In November 2020, McDonald's gave out toys of this ride that could form a 10-car train when fully connected. Just a week after the toys began their release, they were pulled from McDonald's locations nationwide due to an error in the QR code game pieces found inside the toy packaging and on the Happy Meal boxes. In May 2022, they were brought back to promote the 50th anniversary of Walt Disney World. The line was also reduced to eight toys when the original line has ten.
Milestone Celebration: Disneyland's version of the attraction opened in 2023 as part of Disney's 100 Years of Wonder celebration (which commemorates the 100th anniversary of The Walt Disney Company). 2023 also happens to be the 95th anniversary of Mickey Mouse himself and the 10th anniversary of the shorts the ride is based on.
Saved from Development Hell: A dark ride attraction based on Mickey Mouse has been planned on and off for the parks since the 1970s, but most proposals for such an attraction would end up getting shelved, causing the concept to be stuck in Development Hell for years until it was finally realized via Mickey & Minnie's Runaway Railway.
Swan Song: This attraction marked Russi Taylor's final appearance as Minnie Mouse, as well as her final role.
What Could Have Been: Several decades before Runaway Railway, a Mickey Mouse attraction was originally proposed for Disneyland's planned Dumbo's Circus Land area back in the mid-'70s under the name Mickey's Madhouse, which was designed by Ward Kimball (one of Disney's Nine Old Men) and would've been an indoor wild mouse coaster based on the early black-and-white Classic Disney Shorts from the late '20s-to-early '30s. The coaster was scrapped along with the rest of Dumbo's Circus Land. Funnily enough, while likely coincidental, the land planned for Dumbo's Circusland would later be used for Mickey's Toontown, which is where Disneyland's version of Runaway Railway ended up being located.
General Trivia:
A framed photo of Walt Disney driving the Disneyland Railroad can be found in the unload area.
